Muscovy Ducks - molesting other fowl.

If you are breeding muscovy ducks, keep the ducklings away from other poultry for about one week (and maybe 2). If they are around other ducks from day one, they will try to mate with those ducks (Khaki Campbells etc.) when grown. If raised in isolation for a week or two, they will be very quiet and stick to their own kind when grown. I have done this and it works. Same for raising any ducks. Do not put chicks and ducklings together.
I have raised bantam chicks and KC ducklings together for a few weeks. The drake KC proceeded to try to rape the bantam hens pretty much every day. His duck mate would "incite" him to go after the chickens. It was real pain. They were all running loose in a big walled yard.
Do not try to hatch other duck breeds or chickens under a muscovy female. She will reject them when they hatch and may even kill them. Muscovies know their own species of ducklings. You could hatch them under the muscovy, but you must take them away as soon as they hatch.

I haven't had this experience. This year I hatched chicks, muscovies and turkey poults together and they were all raised in the same brooder with no issues. The ducks grew up to be very well-adjusted. They are all housed together in the same coop but I haven't had any issues with one species messing with another. The species do tend to keep together although I've noticed that the chicks raised with the turkeys do still tend to hang out with them a lot.